Tunnelz

China trip guide

What is the Great Firewall of China?

The Great Firewall is the informal name for China’s national internet censorship system. It filters traffic between mainland China and the rest of the world, which is why Google, YouTube and Wikipedia are blocked on Chinese networks. China doesn’t publish how it works or what it blocks, so most of what’s known comes from outside research.

Updated

Mainland ChinaRest of the world your phone or laptopon a Chinese network THE GREAT FIREWALLgateways the government controls google.comblockedOct 2026wikipedia.orgblockedOct 2026www.apple.comconnectedSep 2026 Mainland Chinayour phone or laptop THE GREAT FIREWALL Rest of the world google.comblockedwikipedia.orgblockedwww.apple.comconnected
Fig. 01
Traffic between mainland China and the rest of the world passes through gateways the government controls. Simplified, and real routes vary. The results are GreatFire’s tests of those exact addresses, on the dates shown.

What it is, and where the name comes from

“Great Firewall” isn’t an official title. It plays on the Great Wall, and a firewall is a system that filters network traffic. The phrase was the title of a June 1997 Wired article by Geremie Barmé and Sang Ye, an early use in print. Researchers trace the system itself to the Golden Shield project of the late 1990s.

Freedom House says it rests on the government’s control of the gateways between China’s networks and the global internet. China’s stated position is in a 2010 white paper: “Within Chinese territory the Internet is under the jurisdiction of Chinese sovereignty.”

  1. June 1997

    A Wired article is titled “The Great Firewall of China”, an early use in print.

  2. Late 1990s

    The Golden Shield project, where researchers trace the system itself.

  3. 2010

    A Chinese government white paper sets out its position on internet sovereignty.

  4. Nov 2021

    A 2023 paper dates its first attempts to spot fully encrypted traffic to here.

  5. 2025

    A paper finds Henan Province running its own extra blocking.

Fig. 02
Key dates mentioned in this guide. Not a full history: China doesn’t publish one.

How it works, as far as anyone can tell

China doesn’t publish this, and Freedom House says lists of prohibited sites are kept secret, though they’re sometimes leaked. So what follows comes from researchers’ measurements. Each is from a point in time, and things may have changed since.

  • False address replies. When your device looks up a blocked site’s address, the firewall sends a fake answer, which often arrives before the real one.

  • Reading the site name. The start of an encrypted connection usually shows the name of the site you’re opening. If it’s on a blocklist, the firewall ends the connection.

  • Blocking server addresses. Connections to some internet addresses are blocked outright.

  • Spotting encrypted traffic. A 2023 paper found that from November 2021 it tried to recognise traffic that looks fully encrypted and block it in real time, on part of the traffic to certain data centres.

Fig. 03
Four methods researchers have measured. Simplified drawings: each comes from a point in time, and things may have changed.

It isn’t the same everywhere. A 2024 study describes equipment across China’s border networks, managed centrally, but also saw interference from individual internet providers and cloud companies. A 2025 paper found Henan Province running its own extra blocking on traffic leaving the province.

What it blocks in practice

Freedom House’s 2024 report lists these among the blocked sites and apps:

Google

  • Search
  • Maps
  • Docs
  • Drive
  • Translate

Social and messaging

  • Facebook
  • Instagram
  • X
  • WhatsApp
  • Signal
  • Telegram
  • YouTube

Reference

  • Wikipedia
  • Reddit

News and rights groups

  • The New York Times
  • Amnesty International
  • Human Rights Watch

One address at a time: GreatFire’s tests from inside mainland China

  • google.comBlocked
  • youtube.comBlocked
  • wikipedia.orgBlocked
  • nytimes.comBlocked
  • www.apple.comConnected
Fig. 04
Top: among the blocked sites and apps in Freedom House’s 2024 report. Bottom: GreatFire’s results for those exact addresses on those dates. Blocks change over time.

Not everything foreign is blocked, as the www.apple.com result shows.

Blocks also change over time. The UK Foreign Office says access can be restricted around key political events, and Freedom House says VPN blocking tends to tighten before big political events, such as China’s yearly legislative meetings.

What it means for your trip

The blocks apply to traffic on Chinese networks, so how your connection is routed matters, not who you are.

  • Hotel Wi-Fi and other Chinese networks

    The same blocks apply.

  • Some roaming eSIMs

    Airalo’s among them, send your data through a network outside mainland China.

  • A server of your own

    Tunnelz sets one up that only you use. If it’s ever blocked, Replace Server can set up a new one in about 2 minutes, if the app can reach Vultr.

Fig. 05
The blocks apply to traffic on Chinese networks, so the route matters. Simplified drawings; no route is promised to stay open.
  • Do you need a VPN? That has its own guide, including why to set one up before you fly.
  • Phone only? Some roaming eSIMs, Airalo’s among them, send your data through a network outside mainland China. VPN or eSIM compares the two.
  • Hotel Wi-Fi is a Chinese network, so a laptop or phone on it gets the same blocks. The hotel Wi-Fi guide covers signing in.

Tunnelz runs on an Apple silicon Mac with macOS 14 or later and sets up your own server, which only you use. If your server is ever blocked, Replace Server can set up a new one in minutes, as long as the app can reach Vultr. In China that may take eSIM data or another network (how). Tunnelz for iPhone is coming.

Questions

How many websites does the Great Firewall block?
There’s no official number. Researchers’ counts depend on what they test and when: a 2021 study found about 311,000 domains caught by its domain-lookup (DNS) filter over nine months, and a 2024 study about 943,000 by its web (HTTP) filter and 55,000 by its encrypted web (HTTPS) filter over 20 months, to September 2023.
Does the Great Firewall apply in Hong Kong?
Freedom House’s Freedom in the World 2026 report says mainland-style internet censorship hasn’t reached Hong Kong yet. This guide is about mainland China.
Is it legal to use a VPN in China?
China has rules on this. They say VPN services need a government licence. Separately, China’s Cybersecurity Law was amended, and the changes have been in force since 1 January 2026. We’re not lawyers and this isn’t legal advice, so check current official guidance, such as your own government’s travel advice, before you go.

Sources